The present invention relates to a control apparatus and a control method for use with plasma utilizing equipment, and in particular, to a control apparatus and a control method for use with plasma utilizing equipment capable of achieving control of the plasma utilizing equipment at a high speed with high precision.
A control apparatus for a plasma chemical vapor deposition (CVD) facility, a plasma doping device, a sputtering unit, and the like includes a member state detecting section to detect a state of a member to be processed, a plasma probe to detect the state of plasma, a utility monitor to detect a state of consumption of utility, and the like and supplies numerical information items measured by various kinds of measuring devices to a controller. Having receiving the numerical information, the controller executes arithmetic processing for the information to generate control numerical information and controls control devices and the like of the plasma control apparatus according to the information.
Characteristics of plasma in the plasma utilizing equipment have not been completely clarified yet. Therefore, it is difficult to control process parameters of the plasma utilizing equipment in association with changes in process characteristics. The plasma utilizing equipment of the prior art adopts a method in which process parameters set at start of production are kept unchanged.
On the other hand, in plasma utilizing equipment including a reactor to fabricate semiconductor devices, a state of the reactor changes during the fabrication due to reactive products and the like accumulated in the reactor and hence plasma processing characteristics change with lapse of time. To cope with the changes in the plasma processing characteristics, the reactor must be opened to be cleaned or the reactor must be initialized by replacing parts.
With recent increase in the density and the degree of integration of semiconductor devices, high-precision work or machining is required in semiconductor device manufacturing processes. Particularly, in plasma utilizing equipment, the machining precision decreases due to fluctuation of plasma. Therefore, it is essential to exactly control quantity of energy to be supplied to the plasma utilizing equipment and various utilities thereof.
To control plasma with high precision, there is required a controller having high processing capability. In some cases, processing capability of one controller is insufficient and hence delay takes place in the control operation. On the other hand, there is known a method using a plurality of intermediate controllers in which the various measuring devices are classified into a plurality of groups respectively assigned to the intermediate controllers. In this method, it is difficult for a controller corresponding to one group to complementarily or associatively use numerical information measured by measuring devices of other groups.
Recently, a concept of an auto process control (APC) has been introduced to control apparatuses of plasma utilizing equipment. According to APC, attempts have been conducted to achieve process control using various measuring devices. However, interactions exist between process parameters to determine a state of plasma processing and a relationship of tradeoff may exist therebetween. Therefore, in the plasma utilizing equipment, effective process control has not been yet achieved as described above.
In a method to carry out the control operation using a mutivariate analysis, it is required to control a plurality of process parameters for one process characteristic. This requires complicated arithmetic operations, and a large volume of work or processing is necessary to prove or to verify results of the operations. Consequently, it is difficult to practically use this control method.
It is therefore an object of the present invention, which has been devised to remove the difficulty, to provide a control apparatus and a control method for use with plasma utilizing equipment in which numerical information items measured by measuring devices can be complementarily and associatively used and the control operation can be accomplished at a high speed with high precision.
Another object of the present invention is to provide a control apparatus and a control method for use with plasma utilizing equipment in which the control operation can be effectively carried out even when interactions exist between process parameters.
To solve the aforesaid problem of the conventional techniques, according to an aspect of the present invention, there is provided a control apparatus for plasma utilizing equipment including first, second, and third communication links which are connected to each other; a plasma detecting section connected to said first communication link for detecting a state of plasma generated in a vacuum chamber of said plasma utilizing equipment, a member state detecting section connected to said first communication link for detecting a state of a member to be processed, said member being disposed in said vacuum chamber; a utility detecting section connected to said first communication link for detecting a state of a utility of said plasma utilizing equipment; a plurality of controllers each connected to said second communication link for generating control information for controlling energy to be supplied to said plasma utilizing equipment or a utility of said plasma utilizing equipment according to detected information detected by at least one of said plasma detecting section, said member state detecting section, and said utility detecting section; an energy control device connected to said third communication link for controlling energy to be supplied to said plasma utilizing equipment according to the control information, and a utility control device connected to said third communication link for controlling said utility according to the control information.
According to the aspect of the present invention, a plurality of measuring devices to acquire numerical information necessary for the operation of the process control of the plasma utilizing equipment are connected to the first communication link, a plurality of controllers to conduct numerical calculations according to the numerical information are connected to the second communication link, and a plurality of controllers to receive control numerical information generated by the controllers and to accomplish necessary control operations are connected to the third communication link.
As above, since a plurality of controllers are connected to the shared link and the input devices and the output devices are connected to mutually different links in the configuration, the controllers can freely receive numerical information from the various measuring devices to execute concurrent processing and hence the processing of operations can be executed at a high speed with high precision.
According to an example of the present invention, at least one of said controllers includes an extracting section for extracting detected information which primarily influences only predetermined process characteristics and a control information generating section for generating control information for controlling energy to be supplied to said plasma utilizing equipment or a utility of said plasma utilizing equipment according to the detected information extracted by said detecting section.
The selected process parameters are controlled as above so that interactions are minimized between a plurality of process parameters hindering the stability and the process efficiency of the plasma processing, and hence the initial process characteristics can be kept retained for a long period of time. In this respect, the process parameter means control variables for executing the process and the process characteristics means working characteristics obtained by the execution of the process.